chnical manual on small-scale processing of fruits and vegetables FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS Gaetano Paltrinieri Senior Food Technology and Agroindustries Officer FAO Fernando Figuerola Food Science and Technology Expert Loreto Rojas Food Technology Expert FAO REGIONAL OFFICE FOR LATIN AMERICA AND THE CARIBBEAN Santiago, Chile 1997 The authors, Fernando Figuerola and Loreto Rojas are FAO Consultants. The information, names and points of view that appear in this book are the exclusive responsibility of the authors, and as such should not be considered as the expression of any opinion of the Food and Agriculture Organization of the United Nations, with respect to the legal situation of any country, territory, city or area or of its authorities, or with respect to the delimitation of its borders or boundaries. Any reference to specific enterprises, products, brands or certain manufacturers does not mean that they are being recommended by FAO or by the authors over others of the same nature and characteristics that are not specifically mentioned in the text. Contents Preface Introduction Chapter 1 Necessary infrastructure
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chnical manual on small-scale processing of fruits and vegetables
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
Gaetano Paltrinieri
Senior Food Technology and Agroindustries Officer FAO
Fernando Figuerola Food Science and Technology Expert
Loreto Rojas Food Technology Expert
FAO REGIONAL OFFICE
FOR LATIN AMERICA AND THE CARIBBEAN
Santiago, Chile 1997
The authors, Fernando Figuerola and Loreto Rojas are FAO Consultants.
The information, names and points of view that appear in this book are the exclusive
responsibility of the authors, and as such should not be considered as the expression of any
opinion of the Food and Agriculture Organization of the United Nations, with respect to the
legal situation of any country, territory, city or area or of its authorities, or with respect to the delimitation of its borders or boundaries.
Any reference to specific enterprises, products, brands or certain manufacturers does not
mean that they are being recommended by FAO or by the authors over others of the same
nature and characteristics that are not specifically mentioned in the text.
The relationship between production costs and processing
Consistency between agricultural production capacity and processed output
Chapter 8
Cost structure to be considered
Investments
Total operating costs
Chapter 9
The destination of processed fruits and vegetables
Self-consumption
Community consumption
Small-scale marketing
Marketing at a regional and national level
Chapter 1
Necessary infrastructure
When considering the setting up of a fruit and vegetable processing plant, whether it be a
cottage industry or a small industrial scale system, the first point to bear in mind is the infrastructure required to properly lodge all of the necessary equipment.
Some time must thus be devoted to coordinate two aspects that are vital to the
development of a project of this nature, namely costs and the quality of the infrastructure
needed to achieve the established goals.
It must always be borne in mind that since the food to be processed is intended for human
consumption, the infrastructure must meet several requirements. The basic general aspects of such requirements will be analyzed in this chapter.
The infrastructure comprises different aspects of a project's implementation. Issues like
physical layout, basic services or installations and equipment must thus be taken into
account.
Physical layout
The physical layout of a plan of this nature may be very simple, as it refers to a basic
production system, involving small volumes and simple products, from a technological point of view.
Nevertheless, in the case of a cottage industry and a small industrial scale system alike,
simplicity must never neglect the basic principles governing industrial health and hygiene,
which must characterize a food production system.
Production sites
Several different processes take place on the site where the production activity is
performed, from the reception and conservation of raw materials, to the storage of finished products.
One aspect that must be borne in mind relates to construction details, which determine a
plant's capacity to meet two objectives: to adjust to the production of foods and to ensure a
sufficiently long shelf life. However, when considering home or small-scale industrial
processing facilities, the cost of construction is an important factor which must be taken into account.
The building materials must be as light as possible, easy to readapt and install, considering
that often the system users develop the plan themselves, by means of self-construction
methods.
The buildings materials must be easy to readapt because these home-made systems are
rather dynamic, that is, they require frequent changes or must adjust to different processes,
so that the space that they occupy may be exploited all year round. On the other hand,
these systems must be considered "expandable" to accommodate possible evolutions in
time.
In addition to the previously mentioned characteristics, the materials must be easy to wash
and disinfect, especially those in the clean areas of the processing rooms. Complex type of
construction, resulting in the creation of places that are not easily accessible for cleaning
must be avoided, for they may turn into bird nests, and contamination foci for rodents,
insects, and of course, micro-organisms.
Requirements pertaining to the materials and construction characteristics of the sites do not
vary greatly for home processing or small-scale industrial plants. The basic difference lies in
the equipment and the way it is set up in the processing lines. The home-processing system
is temporary and versatile, and there are no special areas devoted to a single process. In
general, all of the premises serve several purposes, according to the type of process and raw material being used.
The small-scale industrial system, on the other hand, is more complex in its organization,
and therefore specific activities are carried out in determined areas. Nevertheless, the
general requirements for both systems are similar, the difference being in the way such
requirements are met.
Some of the aspects that may be considered important in relation to the architectural and construction elements are listed below:
The ceiling and walls of the processing room must be of washable and easily dried materials; they must be neither absorbent nor porous.
- The lighting should be natural, as far as possible. However, if artificial lights must
be used, they should not hinder activities in any way. Artificial lighting must be
protected, to prevent fragments of glass from falling into the product as it is being processed, in case of accidents.
- Ideally, the working environment should always be appropriately ventilated, to
facilitate the workers' performance. Poor ventilation in highly enclosed and densely
populated premises may generate defects. It is also important to provide for the
elimination of heavily contaminating odours, even if they are not necessarily toxic.
On the other hand, excess ventilation, especially in places characterized by great aerial
contamination external to the processing site, dust and insects essentially, may prove to be
counterproductive. Appropriate ventilation must therefore be based on an efficient system controlling the access of foreign material from the external environment.
- The floors must be of a solid material, never earth or plant covering. Like the walls
and ceiling of the processing room, the floor must be washable, to ensure
compliance with the premises' hygienic and health standards. The floor must also be
sloped to allow appropriate drainage, avoiding at all costs the formation of pools in
the processing area. At the same time, care must be taken to prevent the floor from
being slippery.
These are some examples of the features that must characterize a fruit and vegetable processing site to guarantee a quality product suitable for human consumption.
Basic installations or services
Three basic services are required for the operation of a system as the one in question: electrical power, drinking water and the disposal of waste waters.
Occasionally, small-scale industrial plants are equipped with a steam production system, which however is more seldom found in home-processing plants.
Even when a home-processing plant can operate without electrical power, it is better for this
service to be available, essentially to facilitate the processes by means of small devices that
were developed and that improve workers' performance, thus guaranteeing a greater uniformity of products.
Electrical power is also absolutely necessary if one is to rely on an appropriate lighting
system, so that work shifts may be prolonged, especially when there is a surplus production
of raw materials.
In small-scale industrial production systems, electrical energy is indispensable, due to the
greater degree of mechanization of the processes involved. All lights must be installed on
the ceiling at a safe distance to prevent them from getting wet and getting in the way of workers in the processing room.
As to water supply, the problem is slightly more critical. Sufficient drinking water must be
available to ensure the development of a hygienic process, managed by clean people and
with appropriately disinfected equipment. Also, many processes require water, as a result of which water of an appropriate quality must be available.
Since water does not come in abundant quantities, its use must therefore be regulated by
strict savings principles, especially in small or home-processing installations that normally
are not equipped with sophisticated water harnessing devices. Water must be protected
from possible sources of contamination and must be supplied on a continuous basis at all
times. The consumption of water will depend upon the process in question and the design of the production systems.
The supply of water must be ensured on a permanent basis, as a result of which the plant
will need to be equipped with an elevated storage tank to avoid being dependent on the
supply of electricity. A reserve must be created, so that water is available even when there
is no electrical power. Tank storage will also allow for treatment through the addition of disinfectants.
In general, it is advised that chlorine be added to the water supplying the entire plant, so as
to provide for permanent disinfection. To this end, a dose of 2 ppm of residual free chlorine
is suggested. It should also be borne in mind that the tank must be covered and not
exposed to sunlight, to prevent the chlorine from decomposing. As a term of reference, 100
ml of a sodium hypochlorite solution for every 2000 liters of water may be used, assuming
that the hypochlorite solution contains about 50 mgr of active chlorine per litre of solution. This will prevent the water from having any chlorine-like taste.
Basic facilities
A fruit and vegetable processing plant must be set up in such a way as to rely on a number
of basic facilities, which are generally similar in home-processing and small-scale industrial
systems. Figure 1 shows a small-scale industrial production system for the processing of
fruits and vegetables.
Reception of Raw Material
The plant must be equipped with a special area for the reception of raw materials, that is, a
site where the raw material received in appropriate conditions may be stored until it is used
in the process. This site, which may simply be a shed or a more appropriately designed
room, must meet certain special standards in terms of temperature, humidity cleanliness,
and exposure to sunlight. It is important to consider that the quality of most raw materials
covered in this manual rapidly deteriorates. That is, even though many species do preserve
their integrity, their inner quality is subjected to variations if storage conditions are less
than adequate.
It is for this reason that the temperature must be as low as possible; it must be cool. The
raw material must not be directly exposed to sunlight. Since storage temperature is a very
important factor, if a refrigeration system is not available, the material must be collected in the cool hours of the day.
If the storage site is cool, it is important for the humidity to be relatively high to prevent the
material from dehydrating and losing its quality. This problem does not apply to areas with a high relative humidity, in which case the only requirement is to find a cool site.
It is important to underscore that the raw material storage area must not be used for the
storage of other products that may be contaminating, such as pesticides, paint, or cleaning utensils, all of which must be kept in specially designated areas.
It must never be forgotten that the quality of the product will reflect the quality of the raw
material from which it was made; it is therefore important to take this aspect into due
account.
This storage site must be provided with basic equipment for the reception of the material.
The scale and other instruments for primary quality control must be kept in a safe place,
where they will not be damaged. An appropriate place must have an average temperature
no higher than 30°C and a humidity no greater than 70%. The tools must be kept in their
respective cases at all times, clean and dry.
FIGURE 1. Fruit and vegetable processing plant.
FIGURE 2. Double-bottom kettle
FIGURE 3. Hand press
Processing room
The processing room is the main facility in a plant of this type. It is here that the different
materials used in the processing of the raw material are stored. On such premises, a
continuous production line may be set up, or simply an ensemble of small machines
allowing the products to be processed by hand and on a discontinuing basis. Ideally, this
room should be big enough to lodge all of the necessary equipment on a continuous line,
even in barely automated facilities. Even in the case of work benches where the work is
performed by hand, the process must be carried out on the basis of a continuous line, to step up efficiency.
The processing room should ideally be divided into areas where different functions are
performed. This may be achieved by separating such areas physically. Generally, there is a
"dirty" area, that is, an area where the raw material is washed and peeled, and where
operations like pitting, coring, and the removal of inedible parts are performed. This "dirty"
area must not extend to the section of the plant or of the processing room where the
cleanest operations are carried out, like pulp extraction, grinding, cutting and the filling of
containers.
One way of achieving this separation is through the use of light partitions, painted wood
panels used to simply separate one area from the other. Much care should be taken to avoid
contamination by run-off waters. The recontamination of materials that have already been
washed and disinfected is a common problem in home or small-scale industrial processing
plants.
Quality control
Ideally, quality control operations should be performed in small quarters, which may also be
separated from other areas by wood panels, where the basic tests required to establish the
quality of a given raw material or a given process may be performed. This area should
preferably be equipped with a small sink, running water and a counter where tests may be
carried out.
It should be separated from the other quarters so that basic calculations may be carried out in a quiet environment.
Storeroom for finished products
The storeroom is fundamental in a plant of this type. It is often necessary for the product to
remain under observation before being consumed. Sometimes, the products must settle for
a while to achieve a certain level of homogeneity, whereas in other cases the material must
await labelling. Finally, in addition to being able to rely on a room where the material may
be safely stored, it is also necessary to have access to a site where the process may be
completed. Such a place must be clean, the temperature and humidity levels must be
appropriate (less than 25 C° and 60% of relative humidity), and it must be protected from
foreign matter, and naturally, from thieves. It should be easily accessible, so that tests may be performed during product storage, and any problems may be detected on the spot.
Other facilities
Some equipment, due to its nature, cannot be installed in the main facility of a processing
plant. The boiler is an example. If the plant is equipped with a small steam generator, it
should be located outside the processing room, to avoid contamination problems, and at the
same time ensure personnel safety.
A drier is another special system, which should be installed in a rather dry place and not in the processing room, as this is an especially humid area in the plant.
Dehydrated products should normally be very low in moisture, a condition that can only be
fulfilled if dehydration is carried out in an especially dry place, even if an artificial drier is
employed. Otherwise, the energy consumption cost will be very high, since a great amount
of heat will be required to dry the air.
Sanitary facilities
Sanitary facilities are believed to deserve special mention, due to the significant role that they play in preserving health and sanitary standards in a plant of this type.
The conditions in which the sanitary facilities operate, the type of evacuation system serving
the plant, the location of the facilities and the sanitation plan are crucial to the quality of the
process.
One basic condition is for the facilities to be erected in a separate location from the area
where the raw material is received and processed, to prevent possible flooding. The facilities
must be periodically disinfected, and the firm's supervisors must exercise very strict control
in this regard.
It should be borne in mind that even though the current cholera outbreak in Latin America
is viewed as an isolated case, health care should not be a priority in times like these alone.
Indeed, there is always some micro-organism around that may be detrimental to the health of whoever consumes the product.
Sanitary facilities must never be short of water. Its supply must be guaranteed, since the
cleanliness of the toilets will determine the cleanliness of the workers, and the products' sanitary qualities will ultimately depend on the cleanliness of the workers.
Equipment
Figures 2-4 and pictures 1-20 illustrate different implements and machines comprising the
basic equipment required for the home processing of fruit and vegetables. Figure 2 shows a
steam-powered heating system, figure 3 shows a press for the extraction of juice, and figure 4 shows a pulp removing machine.
The most common processes that apply to fruit are drying, preservation, pulp concentration, the manufacturing of juice, nectars and sweets, and concentrated pulp processing.
Home Processing Equipment
Pictures 1 to 4 illustrate milling systems. In the first case, a pulp extractor used for fruit as
well as tomatoes and vegetables is shown. It is provided with a sieve to separate the seeds and skin from the juice, which is the basic raw material to be used in the process.
Picture 4 shows a common hand powder separating sieve.
Picture 5 shows a multiple use kit containing a series of materials for fruit processing. This
kit is used for training courses, but it contains all of the elements which, on a larger scale may constitute the basis for the home processing of various fruits and vegetables.
Picture 6 shows a cooking system easily installed in sites characterized by more precarious
conditions. Some of these systems may be installed indoors using the chimney system shown in picture 7.
Picture 1. Electrically powered pulp extractor. (G. Paltrinieri)
Picture 8. Movable solar drier. (TCP/BKF/6658 Project)
Pictures 8-12 show different easy-to-build drying systems, some cheaper than others, but low-cost in general and fit for the process.
Picture 13 shows a sealer for flexible plastic containers, which is of great use for the packaging of jams, sweets and dried products.
Pictures 14-16 show three bottle capping machines which use crown caps and are frequently
employed in the manufacturing of drinks and sauces.
Pictures 17 and 18 show other items comprising the multi-use kit, a scale and a citrus fruit extractor.
Finally, pictures 19 and 20 show a refractometer, an absolutely indispensable instrument in
fruit and vegetable processing, used to measure the concentration of sugar in products preserved according to this method.
In summary, the materials and equipment considered to be the basis of a fruit and
vegetable home processing plant will be illustrated in the following pages, along with the
minimum requirements for the processing areas, the materials and equipment required to
perform demonstrations and commercial processing of fruit and vegetables. All of these aspects are fundamental to the setting up of small rural agroindustrial enterprises.
Specifications for the building or adaptation of industrial premises
- A processing area (5(10) x 10 m approx.) possibly equipped with a ceiling fan, a
mosquito-net and a room in which to store packaging material, additives and finished products (4 x 4 m). Ample natural and artificial lighting.
- Sanitary facilities outside the processing area.
- Electrical power supply, and to the extent possible, sockets on each wall of the processing area, high up above the ground and away from the humid floor.
- Double dishwasher, preferably enamelled or of stainless steel, with running drinking water.
- Two double gas stoves, with their respective cylinders and regulators. As an alternative, electrical, paraffin or firewood-generated heat may be used.
- Drinking water (in the processing area and surroundings).
- Two enamelled or painted wood tables (180 x 120 x 80 cm approximately), with a galvanized steel or ideally a stainless steel covering.
FIGURE 4. Components and diagram of a pulp extractor.
Materials
- Bottles with crown cork. As an alternative, use between 500 and 1,000 disposable
or returnable beer bottles (of approximately 200-280 ml).
- Between 2,000 and 5,000 metal crown cork.
- 500 glass jars (of 450 gr approximately) with screw-on or twist-off lids.
- 200 glass jars (of 900 gr approximately) with screw-on or twist-off lids.
- Screw-on or twist-off lids for jars of different sizes.
- Adhesive labels for bottles and jars.
- Citric acid, 500 gr, or lemon juice, 3 litres.
- Pectin powder for foods, 2 kg.
- Refined sugar, the amount of which will depend on the volume of the product to be obtained.
- 10 empty sacks of flour (1m x 0.5 m approximately).
- 1 kg of sodium benzoate for foods, optional.
- 1 kg of potassium sorbate for foods, optional.
- 1 kg of sodium metabisulfate, optional.
- Caustic soda.
Equipment
- Scale (from 50 to 100 kg).
- Scale (from 3 to 5 kg).
- Scale (from 100 to 500 gr).
- Hand refractometer (0 - 90° Brix)
- Refractometer (0 - 30° Brix)
- Stainless steel thermometer (0 - 150°C)
- 2 cast aluminium pots with lid (with a capacity of approximately 50 litres).
- 2 cast aluminium pots with lid (with a capacity of approximately 10 litres).
- 2 cast aluminium pots with lid (with a capacity of approximately 5 litres).
- 10 wooden chopping boards (40 x 30 cm).
- 5 stainless steel knives with a thick blade (15-20 cm x 2 cm).
- 5 stainless steel knives with a thick blade (10 cm x 1 cm).
- 5 colanders (25-20 cm diameter) with aluminium mesh.
- 5 plastic trays (40 x 60 x 5 cm).
- 10 plastic buckets (20 litres).
- 10 plastic buckets (10 litres).
- 2 plastic or aluminium funnels (20 cm diameter).
- 2 plastic or aluminium funnels (15 cm diameter).
- 3 stainless steel spoons of different sizes.
- 3 large plastic spoons.
- 3 medium wooden spoons.
- 3 large wooden spoons.
- 2 manual pulp extractors/separators.
- 2 manual cappers for crown cork.
- 5 perforated plastic cases for fruit for 18-20 kg.
Equipment for a small-scale industrial plant
When analyzing the equipment required by a small-scale industrial plant, it may be observed that there are no great differences in terms of basic principles.
The difference essentially lies in the size and application of electrical and mechanized
equipment of a greater unit capacity, probably characterized by a greater resistance and durability, but based on the same technological principles.
In the specific case of a semi-industrial plant, the pots will be replaced by steam kettles,
heating will be provided by a steam-boiler, and a small press as well as an autoclave will be
available. A list of additional equipment that must be installed in a small-scale industrial
plant is provided below.
- A small boiler producing 250 kilos of steam per hour.
- A vertical autoclave with a capacity for about 200-500 g jars.
- A pulper, which operates manually or electrically.
- A hand-operated hydraulic press.
- A pressure bottles closer.
- Two double-wall kettles.
Figure 5 illustrates the procedures involved in the preservation and processing of
concentrates, in which the handling takes place on a larger scale as compared to home
processing. It may also be observed that with the exception of the vacuum evaporator (9),
the rest of the equipment is rather similar to that analyzed in the previous section, with a significant difference in size but governed by the same principles.
Since it is larger, automated to some extent and characterized by a greater use of
electricity, a small-scale system requires installations in better conditions than a home processing system, although such requirements are significant in terms of space only.
In food manufacturing, the staff are the most important resource in the production process.
This is equally true of home and small-scale industrial processing operations, in spite of the fact that they are essentially self-managed.
When speaking of home processing, it is immediately assumed that none of the staff are
hired on the basis of regular employment conditions. The situation thus must be analyzed from a different perspective than that normally adopted for an activity of this kind.
The purpose of these considerations is to stress that even in home or small-scale industrial
processing operations, or in the case of a small group of people, there is a value that must
be duly assessed, namely the labour involved in the process. It should be borne in mind
that even in the case of small businesses, there may be the traditional division between
temporary and permanent staff. The permanent staff will undoubtedly comprise the
entrepreneurs, those who are financially responsible and have set up the small or very small
firm. The temporary staff will comprise workers hired on a provisional basis, as a result of a
seasonal surplus of raw material, who will come to be part of a process that does not involve them financially or emotionally.
Permanent staff
The permanent staff are responsible for the business, and have the greatest interest in the
production activity. They are usually involved in the enterprise on both an emotional and
financial level. In this type of firm, the permanent staff generally include the owners, those
who conceived the idea of setting up the business, the developers, the sales people and the
innovators. It is extremely important for this staff to receive training in the area of management as well as technology, although emphasis should be placed on management.
Temporary or seasonal staff
The training of temporary workers should especially focus on technology; it should be
demonstrated to them how important it is to do things right from the beginning. It should
be borne in mind that in a home or small-scale industrial processing system, the incidence
of labour is of vital importance in the enterprise's financial position.
This chapter will examine all of the aspects that need to be considered in a successful food
processing practice. It will analyze in general terms the sanitary management of a home
processing system, which is very sensitive and often is characterized by serious failures
deriving from the lack o: financial resources.
General sanitary standards
Quality and health standards and regulations must be strictly applied, or the product will be
exposed to contamination by bacteria, mould and yeasts, thus jeopardizing the expected development of an agroindustrial enterprise.
Such measures must be adopted as early as in the production phase, and must continue in the post-harvest, transportation, storage, preparation and processing phases.
In line with these principles, the following sanitary standards must be fulfilled and applied
by workers on the production premises:
- Workers must wash their hands and clean their nails carefully before engaging in
any process. They must keep their nails short, and if possible, use rubber gloves.
- To enter the working area, workers must wear a clean smock, a hair net to protect
the food from possible contamination by hair, and a mask to avoid microbial contamination.
- The working utensils and equipment must be cleaned appropriately to remove any waste or residual organic material.
- The containers (glass jars and bottles) must be washed with hot water before being
filled with food.
- The waste generated by the production process must be removed from the production area on a daily basis.
- Clean and dry the outside of the containers with the product before labelling and storing.
- The storage site of the finished product must be clean and free from all possible
contamination (it must have been previously fumigated). It must also be cool and
dry.
- Once the working cycle has been completed, the production area must be left
perfectly clean. It will therefore have to be pre-rinsed with water at a temperature of
40°C (to remove about 90% of the dirt), washed with detergent, and finally rinsed with water at a temperature of 38-46°C.
- Both the premises and the equipment will have to be disinfected on a fortnightly
basis. Caustic soda will be applied first (2%), and then nitric acid (1.5%) at a
temperature of 75 0 C after which they will be rinsed with water.
Industrial health standards
Whereas hygiene is a principle that applies to people, industrial health applies to the
equipment, facilities and premises utilized in the production process. It is extremely
important to adopt measures to ensure that the facilities meet the industrial health standards which guarantee an efficient implementation of the process.
These standards apply to small, medium and large enterprises and cottage industries alike, and should also be applied at the home level. They may be summarized as follows:
Picture 21. Note the smock, cap and mask to be worn on the job. (G. Paltrinieri)
Picture 22. Washing recyclable glass containers with sand. (G. Paltrinieri)
Picture 23. Storage of clean and sterilized glass containers (G. Paltrinieri)
Picture 24. Bottle and jar, extensively used in small-scale processing. (G. Paltrinieri)
Picture 25. Staff preparing dishes for the "seeding". (G. Paltrinieri)
Picture 26. Inoculated dishes with Petri results of inoculation after 4-6 days at 25-30°C. (Raquel Stagnaro)
Picture 27. Inoculated dishes with results after 4-6 days at 25-30°C (Raquel Stagnaro)
Picture 28. Test results of other dishes after 4-6 days at 25-30' C. (Raquel Stagnaro)
- The buildings must be adjusted so that they can be easily cleaned. There should be no blind spaces inaccessible to the cleaning and disinfection system.
- The equipment must be designed in such a way that no empty spaces are left to
facilitate the accumulation of material that may decompose and cause severe
contamination problems.
- All surfaces exposed to food must be properly cleaned and disinfected, with a
frequency that will depend upon the type of raw material and process being used. Fruit and vegetable residues are generally easy to clean.
- A disinfection process can never be performed on a dirty surface. In order for the
disinfection process to be successful, the surface must have been cleaned
beforehand.
- The products used both in the cleaning and disinfection processes must be included
in the list of products authorized by local health authorities. Special care must be
taken to avoid polluting the environment by using products with an uncertain degradability.
- No disinfection process by itself will ever be able to replace the need for daily compliance with general sanitary requirements.
Picture 21 shows a worker wearing her working outfit, which, as may be observed, she
keeps with great care. Picture 22 shows a group of women workers cleaning recycled glass
containers by washing them with a detergent solution and using sand as an abrasive agent.
Such containers are sterilized in boiling water before they are used, and are stored in clean bowls, as shown in picture 23.
Microbiological tests
To emphasize and help the staff of a food processing firm understand the importance of
industrial sanitation and health, a simple test may be performed. All one needs is the
cooperation of a centre equipped for the preparation of Petri dishes with a general-purpose microbiological culture medium like agar-starch-dextrose, and their subsequent incubation.
A certain number of Petri dishes are prepared and sterilized. If there is no university centre
or a similar institution in the area, a local hospital may be asked to collaborate in the
performance of this task. The dishes must be "seeded" with different elements that may
constitute the source of possible microbiological contamination.
These may include the workers' hands, nails, hair or shoe soles (a smear is made in this
case), the counters in the processing area (SMEAR), skin from the face of staff members
(especially in the area near the mouth and nose), the air in the environment, the water utilized in the process and other elements that one might wish to analyze.
A smear is made by rubbing a sterilized cotton swab on the area to be analyzed and then on
the agar surface. The cotton ball is normally placed on a wooden stick 10 cm long and 2-3 mm thick, so that it forms a small brush.
Picture 25 shows a working group with the sterilized dishes ready to be "seeded". After
being inoculated, the dishes are properly marked, sealed, and are left to incubate at a
temperature between 25 and 30°C. Qualitative findings will be observable after 4-6 days,
and will be sufficient for a general analysis of the working environment.
Pictures 26 to 28 show the-dishes with different elements, some of which have exhibited
remarkable micro-organism development, while others have not been characterized by any
sort of growth process. It is interesting to observe that the particles collected from the
workers' fingertips in the illustrated case did not elicit the development of microorganisms.
The same may be said for the particles collected from the counters and the workers' hair,
which is indicative of excellent sanitary and health conditions. On the other hand, it is
important to observe that the water used in the tests and shown in the picture elicited
minor but detectable microorganism growth. This is an important finding, as the water used
was drinking water drawn from the general water supply system serving the institution involved, which was fed by a supposedly sterile deep well.
It is also interesting to note the contamination developed by skin particles, which in this
case were collected from the forehead and the nose region of a production line woman
worker.
The air from the environment was also found to be highly contaminated, probably by dust,
unlike the sample containing particles from the cough of a worker with incipient influenza. Nail particles showed a small degree of micro-organism growth.
A similar test may be carried out periodically to monitor the general level of the working
environment and to raise the awareness of the staff as to the need for personal as well as
plant hygiene.
Chapter 4
Raw material
General principles
Production systems and their influence on processing
Harvest and post-harvest care as a quality factor
Fruits
Temperate climate fruits
Tropical and subtropical fruits
Vegetables
Warm temperate climate vegetables
Cold climate vegetables
Chapter 4
Raw material
Raw materials are one of the most important aspects to consider in fruit and vegetable
processing. The fruit and vegetables themselves are the raw materials, the reason for the
development of preservation processes. Due to the great number of species suitable for
industrialization, only a few will be mentioned, and of these, greater emphasis will be placed on the ones most commonly used.
The objective of this manual is not to specifically define each of the species. Rather, it is to
provide the necessary elements and principles to allow the producers of raw material of any
nature to explore the possibility of engaging in processing activities.
General principles
When speaking about raw materials, especially those used by industrial firms and
particularly cottage industries, it must be considered that they may have two different origins: they may either grow spontaneously or be cultivated.
In both cases, the quality of the raw material is crucial to the fulfilment of the goals pursued
in the processing and preservation of the product, and also determines the level of profit.
The material must therefore be of good quality and its industrial performance, which is
strongly dependent on the quality of the raw material, must be high. In addition to this, the raw material must meet certain basic sanitary quality requirements.
Production systems and their influence on processing
As stated previously, the quality of a processed product essentially depends on the quality
of the raw material. On the other hand, the quality of the raw material also depends on the way that it is handled during the production process.
This is partly true in the case of species that grow in the wild. It is partly true because
harvest and post-harvest handling also influences the quality of a product. This is the case of species that are highly sensitive to post-harvest handling like berries, for instance.
However, it is not only the harvest and post-harvest processes that have an impact on the
quality of the raw material. The entire production process is important, from planting or
sowing to harvesting. And even before sowing, the selection of the soil, of the genetic
material to be planted and of the geographical location, will undoubtedly have a significant
impact on the final outcome, on the quality of the raw material, and on the processed product.
Of course, some species and specific cultivars or varieties within them, are highly
susceptible to environmental conditions, while others are much more resistant to the conditions of the ecosystem in which they grow.
Some of the vitally important factors in the handling of crops or natural resources are presented in the following paragraphs:
- Utilization of cultivars or varieties suitable to the characteristics of the specific environment.
- Technical management of the levels of fertilization required for an appropriate plant
growth, reconciling yield with a number of quality-related factors which depend on
soil nutrient levels and on the plant. For instance, a proper balance between soil
nitrogen and phosphorus, in many vegetables will determine the quality of their
colour, texture, and development, and their preservation capacity in the post-harvest
stage.
- The control of the plant's water resources is a factor which largely determines final
quality. A material that has been somewhat deprived of water will not be suitable for
processing. Its sugar and organic acid levels will not allow for healthy development.
- The management of all aspects related to plant health is crucially important in the
case of a raw material that must meet minimum quality requirements to be
processed, as health standards will determine final quality. For example, certain
products intended for dehydration present very serious defects when processed from
a fungi infested raw material. Plant health becomes a basic priority in post-harvest
preservation. This is a very important aspect of processing in small-capacity cottage
industries, where part of the harvested material must often be stored with no refrigeration for a short period of time.
Harvest and post-harvest care as a quality factor
Harvest and post-harvest care is an aspect of paramount importance, as fruits and
vegetables are usually rapidly perishable. Therefore, since industrial performance depends
on post-harvest quality, special care must be taken in the period between harvesting of the material and the beginning of processing.
The harvesting method employed and the duration of the harvesting period will also
influence the quality of the raw material. Hand harvesting obviously seems more suitable for
small plots of land, as those which will be the object of the activities of a small enterprise or
a home processing system. In this case, care must be taken to make sure that the harvest
operation is performed properly, at the right time and in a way that will not affect the product.
The transportation of the material to the farm and its preservation, the use of containers
that will not spoil the material, and transportation from the farm to the plant are factors
that also influence the quality of the material to be processed. Very sensitive materials, with
a high respiration rate must be processed rapidly or must be stored at relatively low
temperatures. Less sensitive materials, on the other hand, do not require such care. Pulses,
for instance, must be harvested, transported and subjected to processing very rapidly, for they tend to ripen very quickly.
The post-harvest of such raw materials must be strictly controlled, for they belong to rapidly
perishable species. Of course, the idea is to process high quality material, but it is also
important to process the greatest amount possible of harvested material. Processing is an
alternative way to preserve these products so rich in extremely valuable nutrients, like
vitamins, minerals and fibres. Processing must therefore be placed at the service of the preservation of materials that is normally lost in great amounts for want of care.
Fruits
The basic characteristics of a number of fruits suitable for processing and their most
important processes are illustrated in the following paragraphs.
Temperate climate fruits
These species grow in areas characterized by a temperate climate, that is, where
temperatures are never extremely cold.
They include the following species which have an actual and potential economic importance.
SPECIES SCIENTIFIC LATIN NAME
Apple Pyrus malus
Pear Pyrus communis
Peach Prunus persicae
Plum Prunus domestica
Curuba Passiflora mallisima
Passion-fruit Passiflora lingularis
Blackberry Rubus Glaucus
Cherimoya Annona cherimola
Feijoa Feijoa selowiana
Strawberry Fragaria x Annannassa
Tree tomato Cyphomandra betacea
Tropical and subtropical fruits
Tropical and subtropical fruits include members of the Anacardiaceae family, which
comprises about 59 genera and 400 species. Such species are generally found in tropical
areas and in high temperature zones throughout the world, as in the Caribbean, Brazil,
Central America and Africa. Some plants are considered to be of economic importance, such
as mango (Mangifera indica L.), pistachio (Pistacia vera L.) and cashew nut (Anacardium occidentale L.).
These fruits are generally very fragile and sensitive, and therefore require special handling
and proper storage conditions. Nevertheless, they are in great demand all over the world
and sell at rather high prices, mainly due to the fact that very few countries offer appropriate conditions for their cultivation.
These fruits may be broken down in two groups:
- Fruit trees growing in warm climates of a short, medium and long growth period, of which the following are of great economic importance today.
SPECIES SCIENTIFIC (LATIN) NAME
Mango Mangifera indica L.
Guava Psidium guajava
Pineapple Ananas comosus
Papaya Carica papaya
Coconut Cocos nucifera
Lulo Solanum nucifera
Maracuya Passiflora edulis
- Fruit trees growing in warm climates of a short, medium and long growth period,
and of potential economic importance:
SPECIES SCIENTIFIC (LATIN) NAME
Mangosteen Garcinia sp.
Carambola Averhoa carambola
Tamarind Tamarindus indica L.
Sapote Matisia cordata
Guava (Coronilla) Psidium araca
Soursop Annona muricata L.
Breadfruit Artcarpus altilis
Tacay or Inchi Cardiodendron sp.
Caimaròn or uvilla Pouroma sp.
Borojò Borojoa patinoi
In the following paragraphs, some general background information will be provided for
some fruits with an industrial potential.
Banana
Only a very small part of the banana production is preserved by means of drying, freezing
and canning, although such preservation processes are quite important in the areas where these fruits are grown extensively.
The most common industrial forms are dehydrated bananas and banana flour. The latter is
produced from fully developed green bananas. Such products are mostly manufactured in
Ecuador, Brazil and Costa Rica, among other Latin American countries. Most banana flour is
processed with drum dryers, as with spray drying great quantities of product are lost
because the material sticks to the equipment. It should be noted that while banana products
like flour and pancakes are processed from a well developed and green raw material, in the
case of dehydrated bananas the raw material must be ripe.
The varieties most used for dehydrated and dried products are Gros michel, Cavendish, Lady finger and Plantain.
Citrus fruits
The industrialization of citrus fruits requires a raw material with a uniform shape and size.
The varieties with a thin and sufficiently hard rind are preferred, as those with a soft rind, like mandarins, require special handling in the preparation and juice extraction processes.
The products obtained from citrus fruits include orange juice in the concentrated and frozen
form, and by-products like essential orange oil, washed pulp juice, frozen concentrate, concentrate for animals and d-limonene.
For juice processing, it is essential to use varieties with a high juice content and a good
Brix°-acidity balance. The colour is an especially important quality standard in concentrated
orange juices, and in the preparation of citrus product bases. Juices squeezed at different times are usually combined to obtain a product with a balanced colour and taste.
Since vitamin C is the most important nutrient in citrus fruit juice, it should be present in
great concentrations in the form of ascorbic acid. Another processing requirement is that
the raw material must not have an excessively bitter flavour, or that it does not acquire a bitter flavour as a result of thermal processing.
Citrus fruit segments are another derived product. When citrus fruit segments are
packaged, it is extremely important for the raw material to have a firm and seedless
texture, as deseeding is a very time-consuming and expensive process which spoils the fruits, making them less attractive to consumers.
Grapefruit, mandarin and orange segments are in greatest demand. These fruits must preferably be fully ripe.
Fig
Figs are very suitable for being canned, dehydrated, presented as paste and processed into frozen products or into compote. In their fresh state, however, they spoil rapidly.
They are difficult to transport and cannot adapt to storage conditions, not even if they are refrigerated.
Figs intended for dehydration must be left to fall from the tree when they are ripe. They
must be picked from the ground frequently, to prevent hardening of the skin, the growth of fungi and attacks by insects.
Tree tomato
This fruit is characterized by the fact that it has an ovoid-apiculate shape, that it is green in
colour when unripe and reddish-orange when ripe. It is between 6 and 9 cm long, and its
widest part measures between 4 and 6 cm. Its average weight may range between 70 and
80 grams. Its skin is thin, smooth and resistant, the pulp has a very pleasant and peculiar flavour, and many seeds are concentrated in the middle of the fruit.
This fruit is currently used to make home-made compotes, to make drinks by homogenizing
the pulp with water and sugar, to produce spicy sauces, and as seasoning to prepare certain dishes.
Carambola
The carambola is also known as star-fruit; it also has other specific names, according to
geographic location. It originated in Ceylon and in the Moluccas, and has been grown in Asia
for a very long time. It may be propagated in tropical and subtropical climates and is grown
in Australia, the Philippines and other islands of the South Pacific, Central America, South
America, the islands of the Caribbean, Africa, Israel and subtropical areas of the United
States.
The carambola tree is relatively small and is 6 to 9 m high, its crown being between 6 and
10 m wide. Its leaves are dark green, its flowers have a colour ranging between pink and
purple, and a diameter of 6 mm.
The shape of a carambola is between oblong and ellipsoidal, it is between 6 and 15 cm long,
with 4 to 6 longitudinal sections, so that when it is cut into cross sections, the fruit has the
shape of a star. Its skin is translucent, soft and waxy, and its colour ranges from white to a
deep golden yellow. Its taste varies between sweet and sour. The carambola is used to
produce juice, nectar, pulp and jam. It may also be preserved in syrup, after having been cut in cross sections.
Lulo (Naranjilla)
The lulo or naranjilla, as it is also known, grows better in the humid valleys of the Andes near Ecuador, at an altitude between 1,200 and 2,100 m.
In Ecuador, where it originates, the species is found throughout the country, from the
Colombian border to the south, in the Loja province. In Colombia, the main production area
is located between Cali and Ipiales.
The fruits are round or slightly oval-shaped, of an orange-yellow colour, with a short
peduncle of sepals similar to those of the tomato, adhering to the fruit. As a result of the
orange colour and the smooth and resistant aspect of the skin, as well as the predominantly
sour taste of the pulp, resembling that of an unripe orange, the fruit is commonly known as
"naranjilla" (little orange).
The fruits weigh between 40 and 70 g, and their diameter is comprised between 4 and 5
cm. The internal part of the fruit resembles that of a tomato. The pulp is juicy, of a greenish
color, and it is divided in four almost symmetrical sections. The seeds are smooth and roundish, with a diameter of 3 mm and light yellow in colour.
By industrially processing this fruit, the following products may be obtained: nectars and
juices, frozen pulps, 65 Brix° concentrate, jams and jellies.
Blackberry
Numerous species of blackberries or brambleberries have been found to grow in the high
areas of tropical America, especially in Ecuador, Colombia, Panama, Central American countries and Mexico.
The Rubus and Rosa genera, which belong to the Rosaceae family, are very similar, which is
why the blackberry plant rather resembles wild rose plants, with thorns and composite
leaves behind five leaflets. The differences between these genera lies in the fruit, as
blackberries look like oblong or thimble-shaped strawberries, and when they are ripe they acquire a black, red or purple color.
There are believed to be as many as 300 species of blackberries of a relative importance
throughout the world, according to the commercial value that they are attributed in the
different areas.
The following industrialized products may be obtained from this fruit: nectars and juices,
frozen pulps, 65 Brix° concentrate, jams and jellies, 33° Brix concentrates, wine and sulfite
pulps.
Cashew
Cashew trees originate from the southern tropical regions like Mexico, Peru, Brazil, as well
as Eastern India. However, they are grown in the tropical regions of America, Asia and Africa.
The cashew tree has an average size and can reach a height of 12 m. The fruit (apple) is
rhomboidal in shape and is between 5 and 20 cm long, 4-8 cm wide, with a slight red,
yellow, or red and yellow skin, which is thin and waxy. The pulp is soft, juicy, yellow,
astringent and sour.
Cashews grow better in tropical climates at an altitude below 100 m. They tolerate different degrees of exposure to sunlight, but cannot withstand the cold or floods.
Cashew apples are rapidly perishable. However, the people of India and Latin America consume them in their fresh state and also process them into juices, wines and syrups.
Soursop and Cherimoya
These fruits are rapidly perishable, and must be hand harvested when completely ripe, to
prevent them from falling from the tree branches and bruising. The ripe fruit is washed with
chlorinated water to remove the soil and minimize the presence of bacteria. Once it is
washed, the fruit is peeled and the pits are removed by hand, for there is no current alternative to this procedure.
Soursops and cherimoyas may be consumed as a dessert, although they are mostly used in the form of frozen pulp in foods like ice cream and syrups, and in drinks.
The diluted pulp may be used to produce nectars and juices with special characteristics. The
frozen puree is sold with added sugar, up to 59° Brix. Storage life may be prolonged by
adding ascorbic acid in concentrations of up to 10-30 g/100 kg. Other products include the combination of soursop pulp and refined tamarind puree and sugar cane or papaya juice.
Guava
The characteristics of a few varieties of this species have been established. Guava is an
excellent source of ascorbic acid (vitamin C), and to a lesser degree, of vitamin A,
phosphorus, pantotenic acid and B complex vitamins. Its seeds may find a potential application in the production of pectin and oils.
The fruits must have a nice colour, a pH near 3.4 and a solids content between 9 and 12%.
The market requires large completely ripe fruits with a firm pulp. Their industrial potential
derives from the fact that they may be used to make pulps, purees, powder for nectars,
jams, jellies and sweets of 70-75 Brix° (ate).
Mango
Like many other tropical fruits, during thermal processing mangoes undergo chemical
changes in terms of their nutritional and organoleptic properties, mainly flavour. It is
therefore important to employ procedures that will not affect such thermolabile compounds
to a significant degree, like freezing or carefully performed thermal techniques, even at a home-processing level.
Mangoes may be processed into different products, such as puree, frozen pulp, nectar,
concentrated and frozen pulp and in a high-sugar pulp preparation known as "ate". Mango
pulp may also be dehydrated to produce bars. Mango slices in syrup or in the dehydrated form are also consumed. This fruit is also excellent when pickled.
Papaya
In addition to being widely consumed as fresh fruit, papayas have other applications as food products.
Like other tropical fruits, papayas are prepared and preserved according to different
methods. Nectars or juices may be produced by using papaya puree, which either alone or
in combination with different-flavoured fruits makes a very tasty product. Papaya pulp is also a very popular product.
Tamarind
This species belongs to the leguminosae family, and every part of the tamarind tree, namely
the wood, bark, leaves and fruits, may be used in many different ways. The tamarind has
been utilized as medicine since ancient times, for its pulp can combat scurvy and has
laxative properties, while its leaves have diuretic properties. However, the tamarind is
mostly used as food. The seeds, the soft leaves and the flowers of fully grown trees are
utilized in salads and to make soups. Unripe and tender husks are used as seasoning in boiled rice, fish and meats.
The pulp obtained from a ripe fruit is an agroindustrial product of considerable economic
value in many parts of the world.
The pulp of the fruit is slightly difficult to extract due to its low water content and, because
it is sticky. To remove it, the fruit is normally subjected to a steam bath for several hours. A syrup of about 13.2° Brix may thus be obtained.
Vegetables
Vegetables may be divided into the following categories, on the basis of their capacity to adapt to different climates:
Warm temperate climate vegetables
Group A: Vegetables that adapt well to temperatures ranging between 18 and 27°C. They
do not tolerate frost. This group includes sweet corn, beans, lima bean, tomato, bell pepper,
squash, cucumber and melon.
Group B: Crops characterized by a long growth period, which thrive in areas where the
temperature is above 21°C. This group includes the watermelon, sweet potato, eggplant
and chili pepper.
Group C: Tropical species growing in very humid areas where the temperature is high. This
group includes the "bilimbi".
Cold climate vegetables
Group D: These vegetables thrive in areas where the mean monthly temperatures range
between 15 and 18°C. They are intolerant to temperatures between 21 and 24°C, and
tolerate weak frosts. This group includes spinach, lettuce, broccoli, beetroot, Brussels sprout, cabbage, radish, rhubarb and watercress.
Group E: These vegetables thrive in areas where the temperature ranges between 15 and
16°C. They do not tolerate temperatures between 21 and 24°C. They may be damaged by
frost when approaching maturity. This group includes the cauliflower, artichoke, lettuce, green pea, white potato, celery, carrot, chicory, endive, parsley and chard.
Group F: These vegetables adapt well in areas where the temperature ranges between 13
and 19°C. They are tolerant to frost. This group includes the onion, asparagus, garlic, leek
and shallot. Some of the vegetables suitable for industrial processing are presented in the following paragraphs.
Tomato (Lycopersicon lycopersicum)
The tomato is a plurannual or perennial plant cultivated as an annual, which belongs to the Solanaceae family.
The fruit is a berry with 2 to 9 loculi. The fruits with many loculi generally have an irregular shape. Their weight ranges between 40 and 300 g.
The tomato is one of the vegetables that enjoys the greatest consumption, both fresh and
as a preserve, paste, juice and dehydrated product.
Bilimbi
The bilimbi may be found throughout South-eastern Asia and across Malaysia, which is its
region of origin. However, the bilimbi is only known as a species crop. The bilimbi was introduced in Australia, the Caribbean, South and Central America, Florida and Hawaii.
The bilimbi tree can reach a height of up to 18 metres, although it is usually 15 metres tall
or less. The bilimbi fruit is cylinder-shaped, between 5 and 7.5 cm long, although its length
is usually 5 cm. It is yellow-greenish when ripe, and its skin is thin and soft. Its pulp is green, soft, juicy and very sour, with few seeds.
The bilimbi adapts better to heat, grows well in humid tropical areas, and cannot tolerate
freezing temperatures. Young trees may be damaged by temperatures between -1 and -2°C.
The bilimbi is not an important product on the world market as a fresh fruit, although it is processed into jellies, sauces, pickles and - juices.
Eggplant (Solanum melongena)
Eggplant is native to India. It is a perennial solanaceous plant, but is cultivated as an annual.
Its fruit is spherical, elongated and pear-shaped or cylindrical. Its colour is purple when it is
ripe, due to the presence of anthocyanin. Some varieties have white fruits. Its pulp is cream coloured and crumbly.
Eggplant may be used for the preparation of preserves in brine and oil, in frozen vegetable mixes, and pickled.
Bell pepper - Chili pepper (Capsicum spp)
There are two types of pepper, the sweet and the hot pepper, the former being used more extensively.
It is a perennial solanaceous plant, grown as an annual. The fruit comprises a composed
pericarp, an endocarp and seeds. Inside, it is divided into lobuli. The shape and size of the fruit varies according to the different varieties.
The colour of the fruit is determined by lycopersicine and carotene, and the yellow by the
xanthophyll. The scent is determined by its ethereal acid content. The fruit also contains carotene or provitamin A.
Its pungency (degree of spiciness) is determined by the alkaloid called capsicine, whose
content ranges from slight traces to 0.71%, mostly concentrated in the pulp.
The product may be consumed directly, or in the form of preserves, pickled peppers or
powder.
Carrot (Daucus carota)
The carrot is an umbelliferous biannual root. It is rich in calcium, phosphorus, iron and carotene (vit. A).
This root is mainly used to prepare pickles and dehydrated products, and is employed in
soup mixes, preserves and frozen products, either alone or in combination with other foods. Carrots may be consumed cooked, in syrup and in the form of juice and jam.
Green pea (Pisum sativum)
The green pea originated in Ethiopia and in Mediterranean Europe. It belongs to the
Fabaceae family (ex Leguminoseae). It is a climbing, herbaceous annual and requires an amount of water equivalent to 45 cm.
Horticultural green peas may be consumed directly, or as preserves or frozen products. In
agriculturally advanced countries, preserved and frozen peas are increasingly taking the
market share of fresh peas. Dried grains are used to prepare pre-cooked flours and soups.
Dry bean (Phaseolus vulgaris)
The dry bean is native to Mexico, Peru and Bolivia and originates from the Phaseolus
aborigeneus.
It is a leguminous plant, which reaches between 105 and 120 cm, and is distributed extensively on the superficial layer.
The fruit is a pod composed by a pericarp and seeds. For green beans, it is preferable to
avoid the formation of parchment between the fleshy parts of the pericarp. The formation of
"strings" or "fibres" in the seams of the pod should also be avoided. The dried fruit may be
used to prepare soups and dried vegetable mixtures, it may be pickled or employed in the preparation of acidified preserves.
Horticultural beans are consumed directly, both in the green pod as grains and therefore
half-ripe, or as preserves. They may also be consumed in the frozen form. Green beans
have a low-calorie content, and a high nutritional value because they contain vitamins,
minerals and carbohydrates.
Onion (Allium cepa)
Onions are bulbous vegetables, important both in terms of domestic consumption and
export. The bulb is consumed in its tender state, raw, ripe, pickled or in form of powder. At
a nutritional level, it stimulates appetite even if its calorie content is normal, its protein and dry material content is low, and its vitamin level is not very high.
The bulbs may be red, white or yellow in colour.
Leek (Allium porrum)
The leek originated in the Near East. It does not form bulbs. It is consumed on a small scale
in soups, contains less volatile oils than garlic and onion, and is rich in organic sulphur. It is mainly used as a dehydrated product in the preparation of sauces and soups.
Garlic (Allium sativum)
Garlic is native to Southern Europe and Central Asia. It is an annual, of the Amarylidaceas
family. The bulb is characterized by antiseptic, diuretic, expectorating, anti-scurvy and
antirheumatic properties. It is consumed directly, in the dehydrated form, and may be used
in the preparation of pickles and sauces.
Asparagus (Asparragus officinalis)
The asparagus is a perennial vegetable, which contains a high level of thyamine, riboflavine
and ascorbic acid. It is consumed in the direct form or as a preserved product. It is native to Europe, the Caucasus and Siberia.
The asparagus belongs to the Liliaceas family. It is made up by a mass of rhizomes with
buds on the tip, which give origin to the edible spears. The stalk or turions have a diameter
between 6 and 23 mm and grow from buds on the rhizomes. This vegetable is especially used for making dehydrated products and soups.
Artichoke (Cynara scolymus)
This crop is indigenous to Southern Europe. Although it is considered to be a perennial
plant, it actually is not, for after it blossoms it dies and is replaced by a shoot. The artichoke belongs to the Compuestas family.
Artichokes are consumed cooked, and the edible portion is the base of the bracts and the heart. Such parts may also be preserved.
Parsley (Petroselium crispum hortense)
Parsley is used as seasoning in soups and sauces. It is a biennial plant and belongs to the
family of Umbeliferas.
Coriander (Coriandrum sativum)
This crop is native to southern Europe. It belongs to the family of Umbreliferae. Its leaves are used for seasoning, and its seeds are used to make liquor.
Sweet basil (Ocicum basicilicum)
The green or dried leaves of this plant are used as aromatic flavouring. The crop belongs to the Labiadae family.
Cabbage (Brassica oleracea var. capitata var. subauda)
Cabbage is a very important vegetable due to its high yield. It is used directly in soups or
stews and is processed into a fermented product. The crop is native to Asia Minor and the eastern Mediterranean region.
Cauliflower (Brassica oleracea var. botrytis)
Cauliflower may be consumed directly or pickled. It is indigenous to the island of Cyprus. It
may be used to prepare pickles, alone or in combination with other vegetables.
Cucumber (Cucumis sativus)
Cucumber is consumed directly in salads and pickled. It is not very important from a
nutritional point of view, as it has a 95-96% water content and few vitamins. It originated in
the humid areas of India, and was later exported to China and South-eastern Asia.
Cucumber may be used to make dehydrated products, it may be preserved in oil or vinegar
or be processed into naturally fermented pickles.
Pumpkin (Cucurbita spp)
Pumpkin is important in terms of its composition and of its relatively high yield. It may be
consumed directly in stews and in pies or in syrup. It is native to Central and South
America. The plants are annuals and bear large fruit that may even weigh 50 kg. Their pulp
has a variable thickness and may be white, off-white, yellow, etc. in colour. The pulp may be used to make pies or it may be preserved as acidified and sterilized pieces in syrup.
Zapallo hoyo and zucchini (Cucurbita spp)
The so-called zapallos tiernos include hoyo, zucchini and hoyito. They may be consumed
when they are still unripe in soups or stuffed. Their vitamin and sugar content is lower than
in that of pumpkins.
These vegetables have an elongated shape, their surface is rough and they are dark green
in colour. Zucchini may be preserved as dehydrated products or in oil, after having been sterilized.
As shown in pictures 29 to 53, the great diversity of raw materials existing both in this
region and in the rest of the world, is such that it would be impossible to engage in an
exhaustive analysis of all of the species suitable for industrialization.
In the specific case of vegetables, practically all species may potentially be subjected to
industrialization processes, with the exception of lettuce, which can only be fermented. The rest of the species, however, are all suitable for processing.
In the case of fruit, the number of both tropical and subtropical species that may potentially be subjected to processing greatly exceeds that of species not suitable for industrialization.
Picture 29. Fruits from dog rose, a wild rosaceous plant growing in south-central Chile. (G. Paltrinieri)
Picture 30. Miniature squashes cultivated in Mexico. (G. Paltrinieri)
Picture 31. Recently harvested broccoli. (G. Paltrinieri)
Picture 32. California-type bonnet peppers. (G. Paltrinieri)
Picture 33. Italian-type tomatoes ready to be harvested. (G. Paltrinieri)
Picture 35. Garlic in plastic nets ready for the market. (G. Paltrinieri)
Picture 34. Cases of recently harvested tomatoes. (Fernando Figuerola)
Picture 36. Onions in nets ready for the market. (G. Paltrinieri)
Picture 37. Bilimbi fruit ready for processing. (G. Amoriggi GUY/86/003)
Picture 33. Carambola fruit washed and ready for sorting. (G. Paltrinieri)
Picture 39. Mangoes ready for processing. (G. Paltrinieri)
Picture 40. Cashew with its false fruit hanging from it, i.e. the nut. (G. Paltrinieri)
Picture 41. Raspberries in trays ready for processing. (G. Paltrinieri)
Quality control tests to be carried out in the laboratory
Chapter 5
Processes
This chapter will present some of the most widely applied procedures in home-made or small-scale processing systems.
General description of the processes
The general concept underlying the preservation of foods aims to prevent the development
of micro-organisms (bacteria, yeasts and mould), to avoid food spoilage during storage. At
the same time, the chemical and biochemical changes that bring about the deterioration
process must be controlled. This way, it will be possible to obtain a food whose typical
organoleptic characteristics will have remained unchanged (colour, flavour and aroma), and which can be safely consumed within a certain period of time (at least a year).
Recently, there have been many innovations in industrial food processing. The techniques
employed today to preserve foods are characterized by different levels of complexity
compared to ancient fermentation and sun drying methods. These include irradiation and
freeze-drying. However, when considering relevant food preservation techniques in small-scale industrial systems, the discussion should be limited to the simplest methods.
Such methods include:
- Canning
- Concentration
- Fermentation
- Dehydration
Preliminary operations
These operations include washing, sorting, peeling, cutting or grinding and blanching, among others.
The raw material must be processed as soon as possible (between 4 and 48 hours after it is
harvested), to prevent spoilage. These preliminary operations are required for the
processing of all fruits and vegetables, which must generally be washed before anything
else takes place (onions and cabbages, for instance, will be washed after the removal of the dry outer layers and external leaves, respectively).
Washing is an operation that generally is the point of departure of any fruit and vegetable
production process. In a small-scale operation, this activity is normally carried out in basins
with recirculating water, or simply with still water that is continuously replaced.
The operation consists of eliminating the dirt sticking to the material before it enters the
processing line, thus avoiding complications deriving from the possible contamination of the
raw material. The washing must be performed using clean water, which should be as pure
as possible, and if necessary should be made potable by adding sodium hypochlorite, 10 ml
of 10%, solution for every 100 litres of water.
It is advisable to use implements that allow for an adequate cleaning of the material, so that no traces of dirt are left in the subsequent phases.
Sorting
Once the raw material is clean, it must then undergo the selection phase. At this stage, the
material that will really be used in the process will be separated from material presenting
some sort of defect, which will become second-choice and will be used for a different
purpose, or will simply be eliminated.
In the case of a semi-mechanized small-scale plant, the selection is carried out on a table
suitable for this process or on a conveyor belt. Such a process will entail the removal of all
of the fruit and vegetables that do not have uniform characteristics compared to the rest of
the lot, in terms of ripeness, colour, shape and size, or which present mechanical or
microbiological damage.
Sometimes, to appreciate the uniformity or quality of a material, it is necessary to cut it in
half to verify its inner contents. Uniformity is a significant quality factor, since it is of utmost
importance for the material to be even and uniform. The function of the sorting process is precisely that of securing such a homogeneity.
Peeling
This operation too is performed on a regular basis. It consists of the removal of the skin of
the fruit or vegetable. It may be performed by using physical devices like knives or similar
instruments, by using heat or chemical methods. Such methods basically aim to bring about
the decomposition of the walls of the external cells of the skin, so that the skin is removed as a result of the tissue's loss of integrity.
Peeling is an operation that allows for a better presentation of the product, and at the same
time fosters sensory quality, for the material with a firmer and rougher texture is
eliminated. Moreover, the skin often presents a colour that has been affected by the thermal processes normally used in processing methods.
Cutting
Cutting is an operation that is usually included in the different preservation processes. This
operation makes it possible to achieve different objectives, like an even penetration of heat
in thermal processes, uniform drying and a better package appearance, since the packed
material is more even in terms of its shape and weight. In the specific case of drying, cutting enhances the surface/volume ratio, which increases the efficiency of the process.
When performing the cutting operation, special care must be taken to fulfil two conditions.
First of all, the cutting tools or devices must produce clean and clear cuts not involving more
than a few layers of cells, to the extent possible. In other words, they must not cause
excessive damage to the tissue, to avoid detrimental effects like a change in colour, and
subsequently a change in the product's flavour. Moreover, the cutting must be performed in
such a way as to allow for a viable industrial performance. A way must always be found for
the cutting operation to supply the greatest possible amount of usable material.
Blanching
This is another widely employed operation in fruit and vegetable processing. It is a form of
thermal treatment, the aim of which is to condition the material in several ways: to soften it
to facilitate the filling of the containers and to inactivate enzymes which cause an unpleasant smell and flavour, as well as defects in the natural colour of the product.
This operation requires great care, that is, it must be properly controlled and the
temperature and time of application are to be closely monitored. Also, the treatment must
be rapidly followed by means of efficient cooling. A high-temperature treatment for a brief
period of time is always preferable. Furthermore, it is best to use steam rather than hot
water in the blanching process, mainly to avoid the loss of soluble solids, like water-soluble
vitamins, which occurs when hot water is used.
The most common method used to perform the treatment is the immersion of the product
packed inside a metal basket in a bath of boiling water or in a pot in which a small portion
of water forms an atmosphere of high-temperature saturated steam. In a more automated
system, a steam tunnel may be used, with a continuous line or a chain conveyor which is
submerged in a hot water bath. In both cases, jets of water are used for cooling.
The operations described above may be applied on a general basis, in different processes.
However, some procedures are intended for more specific applications, such as the removal
of pits, coring, pulp extraction and others, which must be carefully studied on a case-by-
case basis to determine the best way to proceed. In view of the limited scope of this
manual, it would be impossible to provide a detailed description of each of these techniques.
It is thus recommended that the general quality criteria described previously be used to implement such specific operations.
Food preservation principles
Food preservation may be defined as the set of treatment processes that are performed to
prolong the life of foods and at the same time retain the features that determine their quality, like colour, texture, flavour and especially nutritional value.
Food preservation processes require a varied and broad time scale, ranging from short
periods needed for home cooking and cold storage methods, to much longer periods of time
required by strictly controlled industrial procedures such as canning, freezing and
dehydration.
When microbial stability is considered, short-term preservation methods like refrigeration
are inadequate after a few days or weeks, depending upon the raw material, for accelerated microbial development occurs.
In the case of industrial processes, in which the preservation is achieved by commercial
sterilization, dehydration or freezing, microbial development is controlled until the processed
food may be safely consumed. It should also be borne in mind that the use of appropriate
containers is extremely important, for the processes would be completely useless if the containers employed were not able to prevent subsequent contamination.
The preservation of fruit and vegetables entails the integral or partial utilization of the raw
material. In some cases, during the process it becomes necessary to add a packing
medium, syrup or brine, while in others the raw material is used alone, as in frozen
products. The raw material may be processed differently, depending upon the product to be obtained, as vegetables in sauce, soups, jellies, pickles and juices, for instance.
The same raw material may be processed in different ways, as a result of which, different products will be manufactured.
The case of the pineapple is a good example, for the same raw material may be processed
into canned slices or rings, pulps or juices.
In general terms, processing methods may be divided into three groups:
Short-term Processing Methods
- Refrigeration
- Cold storage with modified atmosphere
- Superficial chemical treatments
- Special storage conditions
- Packaging systems involving modifications in atmosphere
Preservation Methods by Chemical Action
- Preservation with sugar
- Addition of sulphur dioxide
- Preservation by fermentation and salting
- Treatment with acids (addition of vinegar)
- Use of chemical additives for microbial control
Preservation Methods by Physical Treatment
- Use of high temperatures
- Use of low temperatures
- Use of ionizing radiation
Most of these methods entail a combination of techniques. For instance, there is a
procedure combining freezing, dehydration and preservation, fermentation and
pasteurization. It will also be necessary to be provided with appropriate containers and
packages protecting the food from microorganisms.
The preservation methods that will be mentioned in this manual are the following: canning,
pasteurization, preservation by the addition of soluble solids (sugar), the addition of acid (vinegar) and the natural drying of fruits and vegetables.
High-Temperature Preservation
The processes that use high temperatures as a way to preserve foods include canned and
pasteurized products (juices, pulps). Such thermal processes involve sterilization or
pasteurization in jars, bottles or other containers serving the same function. Other
containers include tin cans. The bulk sterilization of products and their packaging in aseptic containers is another procedure based on the utilization of ultra high temperatures.
Commercial sterilization
Sterilization as a preservation method may be applied to any product having been peeled,
cut or having undergone some other preparation procedure, provided that it has been
packaged in an appropriate container and sealed hermetically to prevent the penetration of micro-organisms and oxygen.
The purpose of canning, which is based on commercial sterilization, is to destroy any
existing pathogenic microorganisms and prevent the development of those that may cause the product to deteriorate.
Sterilization prevents the survival of pathogenic or disease-causing organisms whose
presence in the food and accelerated multiplication during storage may be a serious hazard
to the health of consumers. Micro-organisms may be destroyed by heat, but the
temperature required varies. Many bacteria exist in two forms: vegetative bacteria, which
are less resistant to temperatures, and sporulated bacteria, which are more resistant. An
analysis of the micro-organisms present in food products has led to the selection of the presence of certain types of bacteria as indicators of a successful process.
"Indicator" micro-organisms are the most difficult to destroy by means of thermal
treatment. This means that if the treatment is successful in destroying them, it will be all
the more so in the case of other more heat-sensitive microorganisms.
One of the micro organisms mostly used as indicators in commercial sterilization processes
is the Clostridium botulinum, which causes serious intoxications in low-acidity foods, a condition which elicits toxin production by the micro-organism.
Heat destroys the vegetative forms of micro-organisms and reduces the security level of the
spores, that is, the resistant forms of micro-organisms, making sure that the product may
be consumed safely by humans.
The products that may be subjected to preservation by means of commercial sterilization
are quite varied. Fruits in general may be processed this way, pineapple and guava being
two examples. They are acidic and very safe in terms of the presence of Clostridium
botulinum, for this degree of acidity does not provide the micro-organism with suitable
conditions to produce the toxin, which is highly dangerous and deadly to humans. Low-
acidity products like most vegetables, may be contaminated by the micro-organism and
produce the toxin during storage.
Due to the afore-mentioned reasons, it is not advisable to process low-acidity vegetables in home settings which do not allow for an appropriate control of the process.
Pasteurization
The application of this method is crucial to the products covered in this course, like pulps or juices.
Pasteurization consists of a thermal treatment that is less drastic than sterilization, but
sufficient to inactivate the disease-causing micro-organisms present in the foods.
Pasteurization inactivates most of the vegetative micro-organism forms but not the spore-
bearing forms, which is why it is suitable for short-term preservation. Furthermore,
pasteurization fosters the inactivation of enzymes that may cause the food to deteriorate.
As with sterilization, pasteurization is performed according to an appropriate combination
between time and temperature.
The processing of fruits and of some vegetables into juices and pulps extends their storage
life. This is made possible by pasteurization, which considerably reduces the number of
fermentative micro-organisms that contribute to the acidification of juice, at the expense of sugars.
The pasteurization of clear and pulp-containing juices and of fruit pulp, provides for their
stabilization so that they can be preserved in combination with other methods like chilling or
freezing. All of these procedures will contribute to guaranteeing the quality and shelf life of the product over time.
Drying
The preservation of foods through the removal of water is probably one of the oldest
techniques. In the past, the process was simplified by directly exposing the product to
sunlight. The crop was spread on the ground directly or over sacks or mats made from plant leaves.
Today, the quality of dried products has improved thanks to a number of factors, including the following.
- The use of dehydrating equipment for solar and artificial drying, which increases the efficiency of dehydration.
- The use of chemical pre-treatment to better preserve the colour, aroma and flavour
of the products.
The fundamental principle on which dehydration is based is that at low moisture levels, the
water activity drops down to levels at which neither micro-organisms nor deteriorating
chemical reactions can develop.
Generally speaking, vegetables with less than 8% moisture and fruits with less than 18%
residual moisture are not favourable substrates for the development of fungi, bacteria or important chemical or biochemical reactions.
There are reactions, such as non-enzymatic browning, which may develop at slower rates in
low water-level environments, but that requires high temperatures. Other reactions include
fat oxidation, which may occur at very low water levels, but which is accelerated by light
and temperature. The container and environment in which the dehydrated products are kept are thus extremely important to guarantee good preservation.
Fruits and vegetables can be dried using simple apparatus, as shown in pictures 8 and
onwards. The quality of the products dried according to these methods is much better than
that of products that are simply spread over the ground to dry in the sun.
It is very important to avoid contamination by dust and other substances that may be the
carriers of micro-organisms which are resistant to low moisture levels, as for example the
excrements or urine of rodents or domestic animals, chemical products, pesticides and
others. The sites used for the drying process must also be very carefully chosen. All of such
risks are greatly reduced when equipment as that illustrated in pictures 8-12 is employed.
The drying time and the product's final moisture level will depend on the location of the
dryer, the climatic conditions of the place and the characteristics of the product. Material cut in small sections and with a greater drying surface will dry more rapidly.
The drying process must be handled with great care, if one wishes to obtain a quality
product. Often, the drying must take place in the shade in order to preserve the product's
sensory qualities, like colour, aroma and texture.
Preservation by the addition of sugar
Sugar is generally added in the processing of jams, jellies and sweets. The fruit must be
boiled, after which the sugar is added in variable amounts, depending upon the kind of fruit
and the product being prepared. The mixture must then continue to boil until it reaches such a level of soluble solids, which allows for its preservation.
The addition of sugar plus certain fruit substances produces a gel-like consistency, which
characterizes the texture of jams and jellies. To achieve this, appropriate acidity levels and
sugar contents are necessary. Some fruits do not contain sufficient amounts of the
substance known as pectin to form a proper gel. In such cases, exogenous pectin must be
added. There is a difference between apples or citrus fruits and berries, like raspberries or
Chilean strawberries. The level of pectin is high in the former and low in the latter.
While the fruit is boiling, after sugar has been added, sucrose - which is the aggregate
sugar - breaks down into its components, fructose and glucose. This determines two major
effects on the product: greater solubility, which prevents crystallization, and a sweeter taste. This process is known as sucrose inversion.
Jams and the other products mentioned are preserved on the basis of a principle named
water activity. It refers to the availability of water that is free to react with and allows the
development of micro-organisms. The lower the level of water activity, the lower the incidence of deteriorating chemical reactions and micro-organism development.
The level of water in jams may permit the development of old. Therefore, if the product is to
be preserved, it must be packaged under vacuum by means of the heat filling method, or
else fungistatic chemical substances, like sodium benzoate and potassium sorbate may be
used, which inhibit the development of fungi. Whenever possible, it is always best to opt for
the first alternative, although it requires the use of glass containers, which are more expensive.
Preservation by means of pH regulation
Most foods may be preserved by heat treatment when the medium has a pH lower than 4.0.
It is for this reason that several methods have been developed which seek to control the pH
through the endogenous production of acid, or the exogenous addition of some organic acid, like acetic, citric and even lactic acid.
The acidification of low-acidity vegetables for commercial sterilization-based processing,
with brief sterilization periods at temperatures around 100°C, is a very practical method to employ in small-scale and even home processing.
The preparation of pickles from different vegetables, by means of natural fermentation with
the production of lactic acid, is also a very suitable method for the preservation of
cucumbers, small onions, carrots, peppers and other crops that are regularly marketed in large volumes throughout the world.
It is important to make sure that the pH is kept at a level of about 3.5, so that the product
will have a pleasant flavour and not taste like lactic acid. Lactic acid is naturally produced by
the fermentation of substrates constituting the material, carried out by micro-organisms.
The acidity of a pickle having been prepared by the addition of acetic acid or vinegar, must
be around 4% and not over 6%, expressed as citric acid. In addition to acid, pickles are also
prepared with salt, which is known to possess antiseptic properties, and at appropriate
concentrations preserves the quality of the product for a long time, as well as enhancing the
product's sensory qualities, like its texture and flavour.
It should be stressed that these natural fermentation processes in brine are produced by
micro-organisms that thrive in anaerobic conditions. Therefore, to obtain a good product, the system must be characterized by a low oxygen content.
The product is immersed in brine, or a small amount of dried salt is added (as in fermented
cabbage) and anaerobic conditions are provided in a polyethylene bag or in a container that
should be as hermetic as possible.
Temperature is an important factor in this type of process. It should be no lower than 15°C, with best results obtained at 25°C.
Application of processes to the small-scale industry
As established previously, small-scale industrial processing does not differ greatly from
home processing, as far as the main principles are concerned. The great difference lies in
the procedures and equipment employed in a low-level industrialized plant.
The processes are similar to those analyzed previously, but their volume is greater, which
makes it necessary to have greater control over the components to be able to manage any problem that may arise during the process.
All of the products that are illustrated may be employed in the same way in a small-scale
process, except for the fact that pots will have to be replaced by double-bottom large
kettles normally made of stainless steel, heated by steam. The process is more efficient
thanks to the advantages afforded by the steam heating system, the preparation time is shorter and inspections will also require less time.
On the other hand, the amounts of raw material will be larger, and this will require greater
promotional efforts in the case of home processes. However, a sound home-processing
system also requires planning in terms of raw materials and goods. As a result, the difference is not so significant after all.
In a small-scale industrial process, the equipment fixed in a solid premise has the
inconvenience of not being very flexible, especially when small quantities of raw materials are involved.
Quality
This is a priority concept when considering food processing, even if home or small-scale
industrial processes are involved. The concept of quality is rather complex although common sense has instilled some idea of this basic principle in our heads.
Quality may be defined as the set of attributes or characteristics which describe the nature
of a given good or service. This means that quality is not synonymous with good quality, as
is often thought. Quality is nothing but quality, with no adjectives; it is a set of
characteristics that must be defined more accurately when describing a given product or service.
The determination of quality is just important a process as the proper food preparation. To
determine quality, one must rely on a system, a defined and systematic methodology. The
best way to go about it is to focus on quality production, that is, apply the good quality
concepts to each and every step of the process that leads to the final product.
The control of the product's quality, as the only quality control method, is totally outdated.
The idea today is to produce properly once and for all. In other words, one should seek to
avoid having to go back to the production line to correct the mistakes made in the previous steps. Having to go back is very expensive in terms of current expertise standards.
It is for these reasons that quality should be an assimilated concept, so that emphasis is
placed on the production of goods that will always be acceptable to the consumers, whose demand is predictable.
Quality control must be intended as a planned activity or as a complete system, with written
specifications and standards calling for the revision of raw materials and other ingredients,
the inspection of critical process control points, and finally the revision of the entire system, including an inspection of the finished product.
Integral quality control program
An integral quality control program must contemplate a series of operations, which are listed in the paragraphs below:
- Inspection of the inputs to prevent damaged raw materials or faulty containers
from reaching the processing area.
- Process control.
- Inspection of the finished product.
- Monitoring of the product during its storage and distribution. This point is generally
disregarded, as a result of which all of the previous quality control efforts may turn out to be fruitless.
It is important to bear in mind that to achieve a good quality product, the following points must be considered:
Processing instructions for each product:
- Specific processing equipment.
- Processing temperatures and times.
- Packaging materials.
- Weight or volume limitations per package.
- Product labelling.
Specifications for each ingredient and finished product, including the measurement of chemical parameters:
- pH.
- Acidity.
- Soluble solids.
Sampling and analysis regulations to ensure the fulfilment of standards.
The production plant must be inspected at regular intervals to ensure the following:
- Sound processing and health standards.
- Compliance with industrial regulations.
- Compliance with safety standards.
- Implementation of environmental control measures
- Promotion of energy conservation.
In the following paragraphs, two examples of the implementation of quality systems applied to fruit and vegetable processes will be presented.
Quality control for the production of juices
• Selection and inspection: one of the most important factors in the achievement of the end
product is the selection of the raw material, which in the case of fruit will have to be firm
and mature, free from insect or rodent bites and free from all signs of deterioration.
• Washing: this operation must be performed with abundant water, to eliminate soil or any
other source of contamination. The water must be potable and contain some sort of disinfectant, such as chlorine in low concentrations.
• Pasteurization: in the case of juices contained in glass bottles, this operation will have to be carried out at a temperature of 70°C for 30 minutes.
• Pulp extraction: in this process, the size of holes in the sieve placed in the pulping
machine will have to be controlled, as it will determine the quality of pulp that is obtained.
For instance, an excessively fine sieve will retain a lot of fibre, which will decrease the yield of the finished product.
• Soluble solids: the concentration of soluble solids will be determined by a refractometer, and will be no higher than 18° Brix.
• Product storage and labelling: the labels must be clean and firmly adhere to the container.
Labels must not be placed on other existing labels, except for the cases in which they
complement the already existing information.
Labels must contain the following information:
a) Name of the product, in big letters.
b) Type, class and grade.
c) Production area.
d) Net contents.
e) Indication of the product's origin.
f) Name or corporate name and address of the manufacturer or distributor.
g) Certification of standard compliance, if pertinent.
h) Additives used.
i) Authorization by the health authorities.
Quality control for the production of preserves: Definition of critical points
Selection of the received fruit: the fruits used to make preserves must not be over ripe.
Rather, they should be firm or they will not tolerate sterilization temperatures and will cause
the preserves to have an unpleasant appearance. Fruit selection must be performed
according to homogeneous criteria; in the case of pineapple, for example, the slices must be of the same size.
Fruit peeling: this operation must be carried out in such a way as to avoid the excessive loss of pulp, for this would have a significant influence on the yield of the finished product.
Packaging: the packaging must be performed in such a way that a minimum head-space is
left to produce the vacuum and allow the product to expand at the different temperatures
which it undergoes during the process. The package must have a head-space of 5 mm after the hot product is filled.
Sealing: this is one of the critical and most important stages of the process, for it
determines to a great extent the quality of the finished product. After sterilization and
chilling, it must be checked that the lids of the jars have a concave shape, for if they are
lifted it means that the product has not been properly sealed. As a result, the product is not
safe for consumption because it is exposed to contamination by microorganisms, mainly yeasts and fungi. Therefore, the product cannot be stored and must be reprocessed.
Sterilization: the sterilization of preserves will be performed by means of an autoclave at a temperature of 100°C for 15-22 minutes.
Yield of the finished product: to assess the yield of the product, one has to proceed in the
following manner:
- Weigh the raw material.
- Weigh the fruit eliminated in the sorting stage.
- Weigh losses like peel, seeds and fibre generated in the peeling and cutting processes.
- Sum up all of the previous weight values.
- Obtain the weight of the fruit pieces ready to be packaged.
On the basis of these assessments, it will be possible to obtain the yield by calculating the
percentage of finished product obtained and the percentage of waste in relation to the
processed raw material, considering that the raw material to be processed has a value of 100%.
Quality control tests to be carried out in the laboratory
Tests will be carried out on the following parameters:
a) Acidity
b) pH
c) Soluble solids
To perform such tests, a laboratory will have to be equipped with the following instruments and materials:
- A 50 cc burette.
- 100 and 250 cc precipitation beakers.
- A burette support.
- A nut fixing the support.
- A potentiometer (pH meter).
- A magnetic agitator.
- 10 and 20 cc pipettes.
- A refractometer.
- A 250 cc glass flask.
- Distilled water.
Reagents:
- Alcohol
- Sodium hydroxide
pH determination: this test will primarily be performed on juices and jams, but may be
carried out on pickles as well.
- The pH value will be determined by means of the potentiometer (pH meter), which
will have to be calibrated with buffer solutions 4 and 7 before every group of determinations.
- If a potentiometer is not available, Litmus paper may also be used to determine the pH.
Determination of the acid content:
Using a potentiometer:
Principles
The method is based on the titration of the sample with a sodium hydroxide solution, using the potentiometer to control the pH.